1 //===-- ResetMachineFunctionPass.cpp - Reset Machine Function ----*- C++ -*-==// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 /// \file 9 /// This file implements a pass that will conditionally reset a machine 10 /// function as if it was just created. This is used to provide a fallback 11 /// mechanism when GlobalISel fails, thus the condition for the reset to 12 /// happen is that the MachineFunction has the FailedISel property. 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/ADT/ScopeExit.h" 16 #include "llvm/ADT/Statistic.h" 17 #include "llvm/CodeGen/MachineFunction.h" 18 #include "llvm/CodeGen/MachineFunctionPass.h" 19 #include "llvm/CodeGen/MachineRegisterInfo.h" 20 #include "llvm/CodeGen/Passes.h" 21 #include "llvm/CodeGen/StackProtector.h" 22 #include "llvm/IR/DiagnosticInfo.h" 23 #include "llvm/InitializePasses.h" 24 #include "llvm/Support/Debug.h" 25 using namespace llvm; 26 27 #define DEBUG_TYPE "reset-machine-function" 28 29 STATISTIC(NumFunctionsReset, "Number of functions reset"); 30 STATISTIC(NumFunctionsVisited, "Number of functions visited"); 31 32 namespace { 33 class ResetMachineFunction : public MachineFunctionPass { 34 /// Tells whether or not this pass should emit a fallback 35 /// diagnostic when it resets a function. 36 bool EmitFallbackDiag; 37 /// Whether we should abort immediately instead of resetting the function. 38 bool AbortOnFailedISel; 39 40 public: 41 static char ID; // Pass identification, replacement for typeid 42 ResetMachineFunction(bool EmitFallbackDiag = false, 43 bool AbortOnFailedISel = false) 44 : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag), 45 AbortOnFailedISel(AbortOnFailedISel) {} 46 47 StringRef getPassName() const override { return "ResetMachineFunction"; } 48 49 void getAnalysisUsage(AnalysisUsage &AU) const override { 50 AU.addPreserved<StackProtector>(); 51 MachineFunctionPass::getAnalysisUsage(AU); 52 } 53 54 bool runOnMachineFunction(MachineFunction &MF) override { 55 ++NumFunctionsVisited; 56 // No matter what happened, whether we successfully selected the function 57 // or not, nothing is going to use the vreg types after us. Make sure they 58 // disappear. 59 auto ClearVRegTypesOnReturn = 60 make_scope_exit([&MF]() { MF.getRegInfo().clearVirtRegTypes(); }); 61 62 if (MF.getProperties().hasProperty( 63 MachineFunctionProperties::Property::FailedISel)) { 64 if (AbortOnFailedISel) 65 report_fatal_error("Instruction selection failed"); 66 LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n'); 67 ++NumFunctionsReset; 68 MF.reset(); 69 MF.initTargetMachineFunctionInfo(MF.getSubtarget()); 70 71 if (EmitFallbackDiag) { 72 const Function &F = MF.getFunction(); 73 DiagnosticInfoISelFallback DiagFallback(F); 74 F.getContext().diagnose(DiagFallback); 75 } 76 return true; 77 } 78 return false; 79 } 80 81 }; 82 } // end anonymous namespace 83 84 char ResetMachineFunction::ID = 0; 85 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE, 86 "Reset machine function if ISel failed", false, false) 87 88 MachineFunctionPass * 89 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false, 90 bool AbortOnFailedISel = false) { 91 return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel); 92 } 93